1. Field of the Invention
The invention relates to a contact release capsule comprising a particle, a chemical payload, and a polymer coating, wherein the particle is impregnated with the chemical payload, and the chemical payload is held inside the particle by the polymer coating until the contact release capsule contacts a surface and a shearing force removes the polymer coating allowing the chemical payload to release outside the particle. The contact release capsule is useful in chemical mechanical planarization slurries.
2. Description of the Related Art
Chemical Mechanical Planarization (CMP) was first introduced in the early 1980's by IBM as a semiconductor manufacturing process used to remove material and planarize a wafer surface. Since then, CMP has enabled the continuous scale down of semiconductor device sizes and the introduction of many new materials, including the use of copper interconnects. The CMP process consists of a polishing pad and an aqueous slurry containing chemicals and abrasive nanoparticles. The wafer surface to be planarized is rotated against the polishing pad which is continuously supplied with slurry. The synergistic combination of mechanical abrasion and chemical etching creates high material removal rates (MRR) and rapid planarization. In depth reviews of the CMP process can be found in the literature, for example see “Nanoparticle Engineering for Chemical-Mechanical Planarization” by U. Paik and J. Park, CRC Press, Boca Raton, Fla. (2009), or “The Effects of Slurry Chemistry on the Colloidal Behavior of Alumina Slurries and Copper Nanohardness for Copper Chemical Mechanical Planarization”, by R. Ihnfeldt, Ph.D. Dissertation, University of California, San Diego (2008).
Currently, CMP is used on a variety of surfaces including aluminum, tungsten, various oxides and nitrides, copper, and nickel, to name a few. Despite numerous advancements in slurry technologies, significant improvements are still needed. Commercial slurry products containing silica, alumina, ceria, ZnO, or TiO as their abrasive nanoparticles have been developed over the last several decades. Manufacturers have even developed composite nanoparticles of porous silica coated with ceria, colloidal alumina spotted with various metals, and metal oxide/polymer nanoparticle composites, see U.S. Patent Application Publication No. 2010/0258528, and U.S. Pat. No. 6,764,574, which are hereby incorporated by reference in their entirety. Chemical components in slurries include complexing agents, oxidizers, corrosion inhibitors, surfactants, and all types of acids and bases to control the pH of the solution.